Question

Which of the elements is a component of cytochrome oxidase?
A. Copper
B. Iron
C. Mercury
D. Cobalt

Answer 1

Hint: The enzyme cytochrome oxidase or complex IV is a large protein complex found in bacteria and eukaryotic mitochondria. It is the last enzyme in the cellular transportation chain of the respiratory electron positioned in the membrane. It earns an electron out of each of four molecules of cytochrome c and converts it to one molecule of dioxygen, adding the molecular oxygen to two water molecules.

Complete answer:
Cytochrome C oxidase consists of 13 polypeptide subunits. It includes 3 copper ions that really are essential for its functioning. It also comprises zinc, magnesium, and two heme groups. Copper chaperones are essential for the assembling of the cytochrome c oxidase network, and abnormalities in the genes encoding such chaperones lead to multiple pathologies. The absence of cytochrome oxidase activity is likely to be fatal. Copper is an important micronutrient used by cytochrome c oxidase (Cox) as a metal cofactor. Cox’s key complex includes a copper atom which is needed for its catalytic action. Complications in biogenesis and copper entry into cytochrome c correspond to mitochondrial human diseases. Cox occurs in three conformational states: entirely oxidized, slightly reduced and completely reduced. Each inhibitor does have a strong affinity to some other state. Both heme a3 and CuB nuclear centres are oxidised in the pulsed state; that's the confirmation of the enzyme which has the maximum activity.

Hence, the correct answer is option A.

Note: The above enzyme Cox catalyses the movement of electrons between two substrates, notably ferro cytochrome c and molecular oxygen. Much of the redox energy involved in this mechanism is being used by the enzyme to move protons from aqueous environment to the mitochondrial region of the intermembrane. Thus, cytochrome c oxidase is a redox-linked proton engine that integrates redox energy to proton transportation.